This invention relates to the testing of various types of guard mechanisms for preventing access to a machine containing safety hazards. Such guard devices can exist alone or in conjunction with interlock mechanisms.
The guards are typically structural barriers that are locked in position and can consist of doors, gates, covers, latches and so forth. They will be variously referred to in this application by the synonymous terms, guards, closures and guard closures. In the usual situation the guards are not intended to be open and are only to be opened when the machine has come to a complete rest. When the guard is open it is intended that the machine has been shut down and will remain in the changed condition until the guard is closed even if there is an attempt to restart or restore the operating state of the machine at the main control box of the machine or from elsewhere.
Guarding devices have long been used to prevent access to hazardous areas of machinery. Unfortunately there is a constant and continuous need to work on industrial equipment and every precaution must be taken to insure that prior to permitting a worker to work on the machinery the machine has come to a complete stop. It thus must be insured that the guards that are ever present to prevent entry into hazardous areas can not be opened to permit access until the machine has in fact come to a complete stop.
The present invention is directed to testing systems and mechanisms for insuring the integrity of the devices that indicate the status of machine operation so that guards may not be opened until the machine is completely shut down. Such devices are known as run down completion detectors which, when operating without fault, determine if the machine components within the hazardous space have stopped moving or not. Safeguarding systems include electrical and electronic components that consists of control and sensing systems with associated circuitry. In addition there are mechanical components that in addition to the guard closure include a lock and very possibly interlocks and run down completion detectors such as 1) motion detectors, 2) zero speed switches or detectors, 3) timing devices that are predicated on the fact that the run down times are known and can be relied upon 4) delay devices that also require that the machine components run down times can be relied upon and 5) interference devices that can be inserted in to the motion path of the machine components to insure that the machine has come to a complete stop.
In addition to the aforementioned devices to insure that the machine has come to a complete rest, mechanical interlocks or motion blockers can be inserted to absolutely prevent the machine from restarting until they are removed.
The current state of the art for testing the electrical and electronic components of the safeguarding systems is quite advanced. Commercial self testing systems are available which continuously or intermittently, remotely or proximally check for electrical/electronic faults in the system for single or multiple guard closures, during the running of the machine or when stopped, with the guard closures closed or open. If a fault is detected during the running of the machine, the machine is stopped. If detected during stoppage the machine can not restart until the fault is corrected.
However, the state of the art for testing mechanical components of the safeguarding systems is very primitive. For example the previously mentioned commercial self testing systems are not designed to detect failure or breakdown of the mechanical components of the safeguarding system while the machine is running. For mechanical failure or breakdown to be revealed to its electrical/electronic sensing system the mechanical exercising of the guard closure is required. There are currently no provisions or devices provided to exercise the mechanical components for testing purposes during running of the machine probably because such exercising would stop the machine. If the machine is stopped and the guard closure is opened then closed the electrical/electronic test systems will detect mechanical failures or breakdowns in the protective system.
There exists the obvious approach for testing the mechanical components mechanically by opening and closing each guard closure manually or automatically to determine if the machine is at rest when the guard closure is first unlocked, if power is interrupted whenever the guard closure is open, and if restart is allowed immediately upon reclosing. This is not a practical testing system, except in very restrictive circumstances, e.g. where there are few guard closures and generous amounts of time available for testing.
Accordingly, it appears to be very desirable that there be a test system for the mechanical testing of the mechanical components of safeguarding systems during running of the machine to detect if they have failed or not. Such systems to be most useful must be capable of testing the machine while it is running without stopping it.
In addition it would be desirable if the testing of the guards could be done in conjunction with the testing of the interlocks systems which are present on machines adjacent to guards to shut down machines when the guards are opened if the machine has not previously been shut down and prevents the resumption of powered operation of the machine while the guard is open.
Novel interlocks, interlock testing, testing systems and methods of testing have been extensively detailed in an application Ser. No. 08/861,328 now U.S. Pat. No. 5,870,317 entitled REMOTE AND PROXIMAL INTERLOCK TESTING MECHANISMS AND TESTING SYSTEMS filed in the names of the present inventors and assigned to the same assignee TRIODYNE INC. as the present invention. The filing date of said application is May 21, 1997 and is incorporated by reference into this application as setting forth in detail various interlock systems and methods of testing interlocks. A provisional application covering the same was filed on Mar. 3, 1997.
Referring again to the instant invention there are testing systems and apparatus for sensing the movement of a force displacement device applied as an opening force to the guard closure. The force of the displacement device may be constant or variable as the test situation demands.
The instant invention directs the testing of the guard closures and the testing of the interlocks to be performed during running of the machine and during the rundown phase of the machine when the machine is shut down. It does so without shutting the machine down due to the testing, as described in this submission and the previously referenced U.S. Pat. No. 5,870,317. This is done so, because for reasons of safety it is important to establish that during running of the machine and during its rundown phase, access is denied to the guard protected spaces containing running machine components, and that the interlocks provide the protection for which it has been designed. The guard closure and interlock testing methods, processes, devices and systems of the instant invention and in the U.S. Pat. No. 5,870,317 are designed to determine if that is the case, or if the case is that any specific guard closure and/or interlock have failed, hence no longer provide the expected protection. These are conditions which would be unknown without testing.
The overall system is illustrated by example, schematically in FIG 1. Examples of a main routine for testing interlocks and guard closures is illustrated in FIGS. 8A, 8B, 8C and 8D and various novel subroutines of testing systems for separate guard closures and in conjunction with closure and interlocking and closure testing mechanisms and systems as illustrated in FIGS. 2-7 and 9-15. An overall description of applicants inventions are set forth under the following SUMMARY OF THE INVENTION and will be described in detail under the DESCRIPTION OF THE PREFERRED EMBODIMENTS.
The present invention includes a first novel system for testing a guard closure with a guard closure lock that is not protected by an interlock and includes the utilization of a program controller that will be connected up to a tester probe that can take various forms, which probe is to be mechanically moved to engage the guard closure. An example of a testing unit is set forth in FIGS. 9-11. The controller will be programmed to activate a guard closure test with the machine running and the guard closure lock allegedly latched. The first test will be to see if the probe will deploy so that the testing can take place. If the probe does not deploy, the guard closure cannot be tested and its failure will be so indicated at the program controller and will call for the scheduling of the necessary tester repair or replacement. If the probe does deploy then a sensor will indicate that the guard closure opens or is open or remains closed. If the guard closure is open the guard closure will have failed the test and if it is not open it will record that the guard closure passed the test. Following this test the probe will be retracted and the sensor will so advise the controller that the probe did retract or did not retract. If retraction of the probe did not take place the necessary repair and/or replacement will have to be scheduled to occur. If the closure passes all the tests it will be so indicated. If it did not pass all the tests there will be a suitable xe2x80x9ctest failedxe2x80x9d warning indicator and depending on how the system is programmed, machine will be shut down or will be permitted to continue to run with the controller indicating the failures that did occur. If the machine shuts down, the guard closure testing system will be deactivated. If it is not shut down the program controller can be scheduled to continue to sequentially test a number of guard closures until the last guard closure is tested. At the completion of the testing of the last guard closure the guard closure test system will be deactivated.
The aforementioned system is an arrangement wherein the guard closure with its guard closure lock is tested and is not subsequently protected by interlocks. Another testing procedure that is an important aspect of the applicants invention is to be able to test interlocks of guards that are equipped with integral interlock-lock devices and which in a typical situation, when the guard is closed, will have the lock latched to the guard. For identification purposes this testing, procedure will be referred to as a second novel system FIGS. 3, 3A, 3B, 3C and 3D.
The integral interlock-lock is typically a device which houses both the interlock and the guard lock in a combined housing. The mechanical testing of the interlock for such a coupled device requires the unlatching of its lock from the guard before the interlock testing can be executed.
In this testing system before the interlock of a particular integral interlock-lock device is tested, the interlock function and the lock function is bypassed so that testing of the interlock and lock will not result in shutting down the machine. In this system a program controller will be activated to show that the testing process is to begin. This particular system will include a mechanism for unlatching the lock and if the lock unlatches by changing its state the change of state is indicated on the controller. If the lock did not unlatch then of course the interlock can not be tested and suitable indication will be made to show that the lock did not unlatch. In this particular situation if it is not desired to shut the machine down the controller will indicate that the guard latching system has to be repaired or replaced. The bypass functions will then be removed to reinstate the protection afforded by the interlock and lock.
Returning to the situation in which the lock did unlatch, the interlock tester will then be activated to move the interlock to its xe2x80x9cguard openxe2x80x9d position. It is to be noted again that various types of interlock testers and testing systems that would be acceptable in the instant system are discussed in great detail in the aforementioned U.S. Pat. No. 5,870,317 assigned to the assignee of the present invention which application is incorporated herein by reference. The details of the interlocks are not important to an understanding of the present invention except to note the following features of faultless interlocks. When an interlock is moved relative to the guard closure it protects, or vice versa, the interlock""s sensing mechanisms changes state. When the interlock and guard closure are brought back together the interlock sensing system returns to its original state. The testing of the interlock is done by producing these relative displacements and determining if the required changes of state happen.
If the interlock fails to change its state to the xe2x80x9cguard openxe2x80x9d state by this test it will be recorded that the interlock failed the test and if it did change state the fact that the interlock passed the test will be recorded.
Since this system is used to test the interlock the interlock tester will as the next step restore the interlock to its xe2x80x9cguard closedxe2x80x9d position and will check if it has thereby returned to its xe2x80x9cguard closedxe2x80x9d state. If it failed to return to the xe2x80x9cguard closedxe2x80x9d state, recording of this will be made and if it did return the fact that the interlock passed the test will be so indicated. Following the aforementioned test the lock will be relatched and the system will be tested to check if the lock did relatch which would be to change its state back to what it was originally. If it did not return to its original state a recording to the effect that the lock failed to relatch will be made and if it did return the controller would indicate that the lock did relatch. Upon indicating that the lock relatched the bypassing of the lock in the system will be removed to restore its original protection. If the interlock passed all the tests this will be recorded, the interlock function will be restored by removing its bypass to restore its original protection and the program controller will sequentially test the interlocks of other integral integral-lock devices. If the interlock did not pass the tests the xe2x80x9ctest failedxe2x80x9d warning indicators and devices will be activated and the machine may be shut down due to test failures and be repaired at that time, or not be shut down and just indicate what has occurred and continue to test other interlock-lock systems until the last one is tested at which time the program controller will be deactivated.
The present invention also includes a third novel system FIGS. 4, 4A, 4B, 4C and 4D comprising a guard closure test routine in which the closures are also protected by interlocks but wherein the locks and interlocks are not integral devices and the interlock is used to make a redundant closure test check. In this testing system one will first select a guard closure to be tested and reset the test routines to their test initiation states in which the guard closure locks are latched. Initially the interlock mechanisms are bypassed so that the testing of the guards will not shut down the machine in the event that the guard moves to the open position when a guard testing device such as a probe is used to attempt to open the guard closure. In addition to bypassing the interlocks xe2x80x9cguard closure test onxe2x80x9d indicators and devices are activated. As discussed in the earlier embodiment referred to as the first novel system the guard closure is tested by deploying a tester probe against the guard closure, and a program controller will indicate if the probe actually did deploy. If the probe did not deploy the test of this particular closure is terminated and the interlock function will be reinstated so that in the event the closure is opened the interlock will function normally, to turn off the machine.
A recording of the inactivity of the probe will be made and a suitable indicator will show that the guard cannot be tested and that necessary repair and/or replacement is required. If the probe did deploy then the amount of probe movement will indicate if the guard closure is closed, open or can be opened. An indication that the guard closure is in an open or opening condition will be recorded indicating that there is a problem with respect to the particular guard in question. If the guard closure is not opened this will be noted and if the interlock is known not to be faulty then the interlock will be used to make a redundant test check of the closure status. A known to be faulty interlock or one of unknown condition will not be used to make a closure test check. If it is indicated by the interlock that the guard is in the open position then the fact that the guard closure did fail the interlock test will be signaled. As the next test step, the closure tester probe is retracted and a test conducted to see if the probe did retract. Failure to retract will be recorded and replacement and/or repair will be scheduled. If the closure and probe passed all the tests the xe2x80x9ctest passedxe2x80x9d indicators and devices will so indicate and the interlock function will be reinstated by removing the bypass to restore its original protection. Any failures will activate xe2x80x9ctest failed warning indicators and devicesxe2x80x9d and shut down the machine or not as desired and then move on to test another subsequent guard closure following the same method as herein aforesaid.
Another method of testing of allegedly locked guard closures which are also protected by interlocks can be done by a novel fourth system FIGS. 5a, 5a-1, 5a-2, 5a-3, 5a-4 and 5b calling for a sequential testing first of the interlock and then the closure. In this embodiment the test initiation states of the interlocks and guard closure test routines are reset and the appropriate indicators and devices are activated showing that the interlock and guard closure tests are being done. Also the interlock function is bypassed so that if the guard is opened by the guard closure test the interlock will not shut down the machine. The testing of the interlock will then be accomplished by changing, the interlock to the xe2x80x9cguard openxe2x80x9d position and then making the appropriate tests and records. If the interlock passes or fails the test this will be recorded and indicated. The interlock will then be restored by its tester to the xe2x80x9cguard closedxe2x80x9d position and checked if it has so returned. If it failed to return to the xe2x80x9cguard closedxe2x80x9d state, recording of this will be made and if it did return the fact that the interlock passed the test will be recorded. Following, the testing of the interlock the guard closure is tested in the same manner as set forth when discussing the novel third system.
Another system that could be employed is one that includes sequential testing of the interlock and then the closure where the allegedly locked closures are protected by an integral interlock-locking, device. This system embodies interlock testing as set forth in the previously described second system, the guard closure test from the previously described fourth system and the redundant closure test check by means of the interlock also from the previously described fourth system.
This fifth testing system FIGS. 6a, 6a-1, 6a-2, 6a-3, 6a-4, 6b, 6b-1, 6b-2 and 6b-3 includes a program controller that is initially programmed to bypass the interlock and lock function and activate the xe2x80x9ctests onxe2x80x9d indicators and devices and includes a locked guard closure. The interlock is tested by first unlatching the lock and testing if the unlatching did or did not occur. If it did not occur a record will be made of this and that the interlock cannot be tested. In this case the interlock will not be used to make a redundant closure test check since the interlock was not tested.
In the event the lock did unlatch by changing its state this system will test the interlock of the integral interlock-lock arrangement, as set forth in detail when describing the second system. Following the testing, of the interlock, the guard closure will be tested as set forth in the fourth system wherein a test device such as a probe is used with respect to a guard and its action tested and the interlock will be used to make a redundant closure test check if the interlock has been tested and if it had not failed the interlock tests.
This fifth system slightly differs from the fourth system since while the closure test probe may not deploy, which is a failure of the closure tester, and will be so recorded and indicated, the integral interlock-lock may pass all tests and thus provision is made to reinstate the interlock function by removing the interlock bypass and also the lock bypass to restore their protective functions and activate the xe2x80x9ctests passedxe2x80x9d indicators and devices. For all tests which did not pass, the xe2x80x9ctests failedxe2x80x9d warning indicators and devices will be activated and the program controller will so indicate, and a choice can be made to shut down the machine or allow the machine to operate while indicating what has occurred.
A sixth novel system FIGS. 7, 7A, 7B, 7C and 7D forming part of applicants invention is a routine for testing, allegedly locked closures protected by interlocks where there is a simultaneous testing of both the closure and the interlock with the same tester. The tester is so constructed that it performs the tasks of testing the guard closure and the interlock by the same action. In this system the interlock and/or tester is compliant base mounted as described in detail in the aforementioned pending, application that is incorporated herein by reference, but the tester and interlock are rigidly linked together. Prior to starting, one will select the interlock/guard closure to be tested and will reset their test routines to their test initiation states. Initially one will activate the xe2x80x9cinterlock/guard closure tests onxe2x80x9d indicators and devices and bypass the interlock function and then test the guard closure and the interlock by deploying the tester probe to the guard closure and testing the closure and interlock. The steps of the test procedure and the action of the tester and its probe are best understood by reference to the descriptions of the flow chart in FIGS. 7, 7A, 7B, 7C and 7D and an exemplary mechanism in FIGS. 12-15.
In this sixth system, if the probe does not deploy then the guard and interlock cannot be tested, therefore the interlock function will be reinstated by removing the bypass to restore its protective function and the necessary repair and/or replacement will be scheduled. If the probe does deploy and the guard closure is open or has opened as determined by the amount of probe movement, it is recorded that the guard closure failed the probe test; if it did not open it is recorded that the guard closure passed the probe test. The program controller will then test to see if the interlock changed to the xe2x80x9cguard openxe2x80x9d state due to the action of the tester probe and it is determined if the interlock passed or failed this test and the outcome is recorded. The tester probe is then retracted and if the probe did or did not retract will be ascertained and it will be recorded and indicated whether the interlock passed or failed the retraction test. If the guard closure, interlock and probe passed all the tests the interlock fiction will be reinstated by removing its bypass to restore its protective functions and the xe2x80x9ctest passedxe2x80x9d indicators will be activated. If all tests did not pass, the controller will activate the xe2x80x9ctests failedxe2x80x9d warning indicators and devices and shut down the machine or not as desired. If the machine is shut down the interlock function will be reinstated to restore its protective function and the xe2x80x9ctests onxe2x80x9d indicators deactivated. If it is elected to not shut down the machine the interlock will remain in the bypass mode and allow the machine to continue to operate and to schedule the necessary repair or replacements for a future time.
It remains to note that the novel systems illustrated and disclosed herein are employed as part of a main routine FIGS. 8A, 8B, 8C and 8D that controls the running of a machine and also directs the testing of its guard closures and interlocks. The testing in question is done without shutting down the machine. This main routine is similar to that described in FIG. 2 for testing interlocks only of the referenced U.S. Pat. No. 5,870,317.
In addition to the various systems discussed above that can be used to test the guard closure either separately or in conjunction with interlocks it may be required to determine whether or not the machine has come to a complete stop before guard locks are allowed to unlatch and the guards are allowed to be opened. In such a situation it is usual to employ run down completion detection devices such as motion detectors, zero speed switches or detectors, timing devices, delay devices, interference""s devices and motion blockers to make a final check if the machine has in fact come to a complete stop. Timing and delay devices are often used to assure that run down has resulted in zero motion by withholding a latch opening signal until the xe2x80x9cworst casexe2x80x9d or longest drift time has elapsed plus a safety factor. For machines that have a very broad range of stopping times, the xe2x80x9cworst casexe2x80x9d time may unduly compromise their utility. Here, it is often advantageous to use motion detectors and zero speed indicators to determine when machine components have come to rest. As a check on the veracity of zero motion devices, interference or motion blocking devices may be deployed before operators are allowed to open guard closures. Such devices may be as simple as setting a xe2x80x9cdog into a gearxe2x80x9d or a xe2x80x9cstick into wheel spokesxe2x80x9d.